1. To shoot, or be shot, usu. with small arms fire,
though the term can be made applicable to other
munitions of lesser or greater destructive force.
It refers chiefly to any one direct hit or number of
multiple direct hits which effectively incapacitate
their target, temporarily or otherwise. Strong con-
notation with so-called punitive damages in gang
warfare.

2. To assasinate, or be assasinated, as in a drive-by
attack. A succinct term for the homicide/s resulting
from any decisive, short-lived street skirmish or
ambuscade of premeditated variety that is carried
out with lethal effect.

"Skitz and Reej got slapped hard last month, and
no-one from the crew knows who hit 'em...."

"Ain't nobody doin' any slapping up in the hood
lately; it's like the new age of peace and prosperity"

A slap is a mini reset mechanism. Similar to percussion maintenance of non responsive harware, this intuitive reflex program designed for humans by humans reverts a previously agitated individual to their default quiet state and is often ensued by harsh verbal output. It may serve various auto-correct functions.
The program is partly based off the "if you can't be a good example to others, be a terrible warning for them" algortihm.